Anyone can write for wikipedia as most people have said in previous answers. I have to admit, I do quite a bit of chemistry research there (although I always double check the information) which is written mostly by those in the field. I have actually looked up some information on the eyes the other day, just to see how accurate the information really is. I was surprised to find the majority of the information was correct, but there were several, rather large, errors which I corrected, although I didn't get all the way through the article with my corrections due to time constraints. Wikipedia is a gret starting point, but they are not infallible. It is best to recheck the information, preferably in books by respected authors on the subject, or trusted websites.